In some twisted logic, the reasoning was that despite the candidate going for test in Category A (50kw+) on a bike known to output 69-odd kw unrestricted (in other words he's not claiming his bike to be restricted) he couldn't prove to the tester that the bike had not been restricted.

Don't lots of modern bikes have rider modes that can reduce or increase the kw output? What do the log books for these bikes state as the kw output? Does this ability to change the kw output have any bearing in the UK on the suitability of bikes for tests?